error creating npc on startup and command Citizens 1.2.1 for CB 1.3.1

[sandrofigo]

2012-08-10 14:18:53 [SEVERE] java.lang.NoSuchMethodError: net.minecraft.server.ItemInWorldManager.setGameMode(I)V 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.npclib.CraftNPC.(CraftNPC.java:18) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.npclib.NPCSpawner.spawnNPC(NPCSpawner.java:73) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.npclib.NPCManager.register(NPCManager.java:153) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.npclib.NPCManager.register(NPCManager.java:178) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.commands.BasicCommands.create(BasicCommands.java:180) 2012-08-10 14:18:53 [SEVERE] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 2012-08-10 14:18:53 [SEVERE] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 2012-08-10 14:18:53 [SEVERE] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 2012-08-10 14:18:53 [SEVERE] at java.lang.reflect.Method.invoke(Unknown Source) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.sk89q.CommandsManager.executeMethod(CommandsManager.java:500) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.resources.sk89q.CommandsManager.execute(CommandsManager.java:392) 2012-08-10 14:18:53 [SEVERE] at net.citizensnpcs.Citizens.onCommand(Citizens.java:208) 2012-08-10 14:18:53 [SEVERE] at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40) 2012-08-10 14:18:53 [SEVERE] at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:168) 2012-08-10 14:18:53 [SEVERE] at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:492) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:878) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:825) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:807) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:44) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.NetworkManager.b(NetworkManager.java:281) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:109) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.ServerConnection.b(SourceFile:35) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:583) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:476) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408) 2012-08-10 14:18:53 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)